Preliminary screening of the relationship of serum lipids to survival of chronic dialysis patients

Do biologic markers predict cardiovascular end points in diabetic end-stage renal disease? A prospective longitudinal study

BACKGROUND

Diabetic patients on hemodialysis are at high risk of death from cardiovascular disease, and research has suggested that various biologic markers of inflammation, oxidative stress and hemostasis may give added value to clinical information for predicting cardiovascular event (CVE)-free survival. This information could be particularly important in evaluating this population for renal transplant, given the scarcity of organs. We hypothesized that in diabetic patients undergoing renal replacement therapy (RRT) these biologic markers would prove useful in predicting event-free follow-up in a prospective study.

METHODS

One hundred and fifty diabetic (76 type 1, 74 type 2) and 27 non-diabetic stable RRT patients were followed for 0.04-13.69 years for CVE (myocardial infarction, coronary arterial intervention, peripheral arterial bypass or amputation, cerebrovascular accident or carotid artery intervention), cardiac and all-cause mortality. Measured biologic markers of inflammation included the following: Il-6, C reactive protein, fibrinogen; of hemostasis: fibrinogen, plasminogen activator inhibitor (PAI), fibrinolytic activity, von Willebrand factor VII (vWF), platelet-selectin, viscosity and of oxidative stress: advanced glycated end products and antibody to oxidized low-density lipoprotein. For each, upper versus lower tertiles were compared for duration of event-free follow-up.

RESULTS

Cardiovascular events prior to study entry occurred in 51.3% of DM1, 54.0% of DM2 and 25.9% of DM0 patients. Subsequent cardiovascular events were noted in 31.6% of DM1, 45.9% of DM2 and 11.1% of DM0 patients. All mean levels of biologic markers at baseline were abnormal (P < 0.05).

CONCLUSIONS

In this RRT population, all biologic marker levels except PAI did not improve clinical prediction of events.

Risk factors for thromboembolic events in renal failure

OBJECTIVES

To determine whether prior thromboembolic events (TE) influence current measures of hemostasis, inflammation and oxidative stress in a population at high cardiovascular risk.

BACKGROUND

Renal failure patients demonstrate a remarkably elevated incidence of TE.

METHODS

Relationships between plasma test results and prior TE history were studied in 78 diabetic and 23 non-diabetic patients with renal failure. TE were defined as myocardial infarction, stroke or vascular surgery.

RESULTS

Markers for inflammation (interleukin (IL)-6, C reactive protein (CRP)), thrombosis (fibrinogen, low molecular weight (LMW) fibrinogen, factor VII, viscosity), fibrinolysis (fibrinolytic activity, plasminogen activator inhibitor (PAI)), endothelial/platelet activity (P-selectin, von Willebrand factor (vWf)) and oxidative stress (antibody to oxidized low-density lipoprotein (LDL), advanced glycated end products) were significantly different from a healthy control population. Dialysis patients with diabetes were twice as likely to have sustained a TE (58 vs. 30%, p = 0.032). Those patients in the total group with levels above the median for IL-6 (p = 0.045), and CRP (p < 0.017) were more likely to have sustained a TE than those with levels below the median. Those diabetic patients with levels above the median for CRP were more likely to have a prior history of TE (p < 0.021). For non-diabetic patients, levels above the median of IL-6 were associated with a prior history of TE (p = 0.027). Multiple correlations for factors of inflammation, hemostasis and oxidative stress indicate that these mechanisms are not independent of one another.

CONCLUSION

Prior TE was associated with markers of inflammation a relationship that may influence the interpretation of these tests which are strongly interrelated in patients at high cardiovascular risk.

Prevalence and clinical correlates of coronary artery disease among new dialysis patients in the United States: a cross-sectional study

Despite the high prevalence of coronary artery disease (CAD) among patients with end-stage renal disease (ESRD), few studies have identified clinical correlates using national data. The purpose of this study was to determine the prevalence and clinical associations of CAD in a national random sample of new ESRD in the United States in 1996/1997 (n = 4025). Data on demographic characteristics and comorbidities were obtained from the Dialysis Morbidity and Mortality Study, Wave 2. The principal outcome was CAD, defined as the presence of a previous history of CAD, myocardial infarction, or angina, coronary artery bypass surgery, coronary angioplasty, or abnormal coronary angiographic findings. Multivariate logistic regression analysis was used to assess the relationship of conventional factors and proposed uremic factors to the presence of CAD. CAD was present in 38% of patients. Of the total cohort, 17% had a history of myocardial infarction and 23% had angina. Several conventional risk factors, including advancing age, male gender, diabetes mellitus, and smoking, were significantly associated with CAD. Of the proposed uremic factors, lower serum albumin levels but higher residual renal function and higher hematocrit values were significantly associated with the presence of CAD. Vascular comorbid conditions, structural cardiac abnormalities, white race, and geographic location were also strongly correlated with the presence of CAD. This national study suggests that several conventional CAD risk factors may also be risk factors for CAD among the ESRD population. This study identifies nonconventional factors such as serum albumin levels, vascular comorbid conditions, and structural cardiac abnormalities as important disease correlates. Future logitudinal studies are required to explore the relative importance of the relationships observed here.

Cardiac disease in chronic uremia: pathogenesis

Cardiomyopathy in chronic uremia results from pressure and volume overload. The former causes concentric left ventricular [LV] hypertrophy, results from hypertension and aortic stenosis, and is also associated with diabetes mellitus and anemia. Volume overload causes LV dilatation, results from arteriovenous shunting, salt and water overload, and anemia, and is also associated with ischemic heart disease, hypertension, and hypoalbuminemia. Decreased major arterial compliance and an early return of arterial wave reflections are also associated with the extent of LV hypertrophy. Cardiomyopathy predisposes to diastolic and systolic dysfunction. The latter results from myocyte death, and predisposing factors include ischemic heart disease and the uremic environment. Ischemic heart disease may be atherosclerotic or nonatherosclerotic in origin. Multiple factors contribute to the vascular pathology of chronic uremia, including injury to the vessel wall, dyslipidemia, prothrombotic factors, increased oxidant stress, and hyperhomocysteinemia. Ischemic risk factors include hypertension, LV hypertrophy, hypoalbuminemia, and perhaps hyperparathyroidism. The clinical consequences of cardiomyopathy include heart failure, ischemic heart disease, dialysis hypotension, and arrhythmias. The adverse impact of ischemic heart disease is probably mediated through the development of cardiac failure.

Outcome and risk factors of ischemic heart disease in chronic uremia

To determine the prognosis and risk factors for ischemic heart disease in chronic uremia, a cohort of 432 dialysis patients were followed prospectively from start of dialysis therapy until death or renal transplantation. Baseline demographic, clinical and echocardiographic data were obtained. After the initiation of dialysis laboratory data were collected at monthly intervals, and clinical and echocardiographic data at yearly intervals. Twenty-two percent of patients (N = 95) had either a history of angina pectoris or myocardial infarction on starting dialysis therapy. Median time to onset of heart failure was 24 months in those with ischemic heart disease on initiation of dialysis, compared to 55 months in those without (P < 0.0001). This effect was independent of age, diabetes and underlying cardiomyopathy. Median survival was 44 months in those with ischemic disease compared to 56 months in those without (P = 0.0001). This adverse impact was independent of age and diabetes mellitus but, when cardiac failure was added to the Cox's model, ischemic heart disease was no longer an independent predictor of survival. De novo ischemic heart disease, not evident on starting dialysis therapy, occurred in 41 (9%) patients. When compared to patients who never developed ischemic disease (N = 296; 69%), significant and independent predictors of de novo disease were older age (P = 0.0007), diabetes mellitus (P = 0.0001), high blood pressure during follow up on dialysis (P = 0.02) and hypoalbuminemia (P = 0.03), whereas anemia was not an independent predictor. LV mass index was 174 +/- 7 g/m2 in those who developed de novo ischemic disease compared to 155 +/- 3 g/m2 (P < 0.001) in those who did not. Concentric LV hypertrophy, LV dilation and systolic dysfunction were independent risk factors for de novo ischemic heart disease. We conclude that ischemic heart disease occurs frequently in dialysis patients, that its adverse impact is mediated through the development of heart failure, and that the most important, potentially reversible risk factors are hypertension, hypoalbuminemia, and underlying cardiomyopathy.